Poly(phenylene ether) is a type of plastic known for its excellent water resistance, dimensional stability, and inherent flame retardancy. Properties such as strength, stiffness, chemical resistance, and heat resistance can be tailored by blending it with various other plastics in order to meet the requirements of a wide variety of consumer and industrial products, for example, plumbing fixtures, electrical boxes, automotive parts, and insulation for wire and cable.
Some parts made from poly(phenylene ether)-based compositions require high flame retardancy. Examples include fuser holders for electrophotographic copiers, fan blades, battery parts for hybrid and electric vehicles, parts for automotive kinetic energy recovery systems, and electric vehicle junction boxes. Poly(phenylene ether) is inherently flame retardant, but it is often blended with other components, such as impact modifiers and flow promoters, that reduce the flame retardancy of the resulting composition even as they improve its processing and mechanical properties. So, flame retardant additives are often required for blends of poly(phenylene ether)s with these other components.
Some molded parts require a flammability rating of V-0 in the 20 millimeter Vertical Burning Flame Test of Underwriter's Laboratory Bulletin 94 “Tests for Flammability of Plastic Materials, UL 94”. This V-0 rating can be difficult to achieve in a poly(phenylene ether) composition, even when flame retardant concentration is increased, and concentrations of flammable components are decreased. And when the V-0 rating is achievable, it often comes at the expense of diminished heat resistance and diminished stiffness.
There remains a need for poly(phenylene ether)-containing parts that exhibit a UL 94 V-0 rating while maintaining high heat resistance and stiffness.